Conventionally, when, for example, a semiconductor device substrate or a liquid crystal panel substrate is moist after the cleaning process, dirt remains on the substrate, bacteria multiply on the substrate, or the like. Thus, in order to completely remove the moisture of the substrate, the substrate must be dried after the cleaning process.
Methods of drying a substrate include a spin dryer drying method in which moisture is removed from the substrate by making use of centrifugal force produced as a result of rotating a spinner at a high speed; a steam drying method in which water, which has clung onto the substrate due to isopropyl alcohol (IPA) steam having excellent compatibility with respect to water, is removed by substituting the water on the substrate with IPA; and an air knife drying method in which moisture of the substrate is removed by high-pressure air.
Of the aforementioned conventional drying methods, the spin dryer drying method and the air knife drying method have the problem that the once-removed water droplets turn into mist, which clings onto the substrate again due to circulating current in the apparatus. When mist is produced, contaminants may get mixed in the mist due to wind pressure, and the resulting contaminated mist may cling onto the substrate, thereby contaminating it. In addition, when these methods are used, the substrate may get electrically charged due to high-speed rotation and high-pressure air.
In addition, when the spin dryer drying method is used, the center portion of the substrate may become negatively charged as a result of high-speed rotation, and thus attract outside air, which contaminates the center portion of the substrate.
The steam drying method requires a facility for controlling IPA which is a flammable solvent, a coolant recovery facility, a facility for maintaining the purity of the IPA, or the like, so that facility costs are increased, and a larger area is required for setting the facilities.
When the air knife drying method is performed, the substrates must be dried one at a time, so that a plurality of substrates cannot be dried all at once in batches, resulting in poor drying efficiency. In addition, the air knife drying method requires a conveyance mechanism and a maintenance mechanism, which may produce dust that contaminates the substrates.
Accordingly, in view of the above-described problems, it is an object of the present invention to provide a new drying method and apparatus capable of reducing the possibility of contamination during drying, reducing facility costs and the setting area, and drying substrates in batches.